It is a common observation in cardiac anatomy and histology that the myocardial tissue composing a heart is made of cardiomyocyte and connective tissue and possesses regular and characteristic tissue architectures. The cardiomyocytes are rod shaped, exhibiting fiber-like alignments, and are found embedded in the connective tissues mainly composed of collagen within the myocardial tissue. It is perceived that thin sheets of the myocardial tissue possessing such architectures are laminated and compose a cardiac wall.
Myocardial tissue architectures have been examined in relation to mechanical properties of myocardium as well as a cardiac function. For example, there has been a report of a simulation method to predict a change in ventricular geometry by finite element analysis, utilizing a cardiac structure model wherein the ventricular geometry and cardiomyocytic orientation are presented by data available in computation (example; see non-patent reference 1).
However, in the conventional methods, there is no example of cardiac structure model which contains an appropriate view of a composite material based on a detailed examination of material specifications of cardiomyocyte and connective tissue. Thus the myocardial tissue has not been fully elucidated in relation to the cardiac function.    Non-patent reference 1: P. M. F. Nielsen and other three co-authors. “Mathematical model of geometry and fibrous structure of the heart”, American Journal of Physiology—Heart and Circulatory Physiology 260, USA, The American Physiology Society, 1991, H1365-H1378